Abstract: A method for characterizing function of an air gun includes measuring, with respect to time, a parameter related to pressure in a charge chamber portion of the air gun. The measurements with respect to time are used to characterize the function of the air gun.

Abstract: Signals of pressure sensors and particle motion sensors located in marine seismic streamers are combined to generate pressure sensor data and particle motion data with substantially the same broad bandwidth. The noisy low frequency part of the motion signals are calculated from the recorded pressure signals and merged with the non-noisy motion signals. The two broad bandwidth data sets can then be combined to calculate the full up- and down-going wavefields.

Abstract: A method is disclosed for separating energy resulting from actuating at least two different seismic energy sources from seismic signals. The sources are actuated to provide a variable time delay between successive actuations of a first one and a second one of the sources. The method includes sorting the seismic signals such that events therein resulting from actuations of the first source are substantially coherent in all spatial directions, coherency filtering the first source coherency sorted signals, sorting the seismic signals such that events therein resulting from actuations of the second source are substantially coherent in all spatial directions, and coherency filtering the second source coherency sorted signals.

Abstract: A method is disclosed for deghosting seismic data. The data include measurements of a vertical component of particle motion and pressure. The measurements are substantially collocated and made at a plurality of spaced apart positions. The method includes transforming the data into the spatial frequency domain, and separating upgoing and downgoing wavefield components of the transformed data. Water surface multiples may also be removed by decomposing the signals made at a plurality of seismic energy source locations into upgoing and downgoing wavefields.

Abstract: Drive assembly for acoustic sources having sound emitting surfaces adapted to be excited into vibration movements, in particular for use in seismic explorations. The assembly comprises an electric rotational motor (17) with an associated axle which comprises an axle part (18) the outer cross-sectional contour of which at least partially in the axial extension of the axle part is non-circular, but preferably smoothly rounded. Further the assembly comprises a number of push rods (21, 22) being arranged radially in relation to the axle (18) and adapted to preferably indirectly at their radially inner ends (23, 24) to be influenced by the non-circular axle part (18) during rotation of the axle, whereas the radially outer ends of the push rods (21, 22) are adapted to excite said sound emitting surfaces (1) into vibrational movement.